Looking Up: Finding the North Star

Friday

Jan 31, 2014 at 1:01 AM

By Peter BeckerMore Content Now

One of the most famous stars in the night sky, as seen from the northern hemisphere, is Polaris, the North Star. It is the brightest star in Ursa Minor the Little Bear, also known as the Little Dipper.

Before we get into this further, here’s how to find the North Star. It is not the brightest star in the sky despite its distinction, or otherwise remarkable, but is a faithful guide for anyone needing to know their way in the night - assuming the sky is clear! Prior to satellite telemetry, ship captains and airplane pilots would navigate by the stars and the North Star was invaluable.

It is the one easily visible star that never seems to go anywhere. As the world turns (no, not the soap opera), the constellations of stars appear to rise in the east and set in the west, in the same way the sun makes its daily trek in the daytime sky (ever see the Sun in the night sky?). Constellations and stars that never set are referred to as "circumpolar." They circle a point in the northern sky known as the North Celestial Pole, right next to Polaris.

Your latitude on the globe is easily determined by noting how high above the north horizon, the North Star shines. As see from Hawley, PA the North Star is almost 42 degrees above the horizon, which is the same as the latitude or degrees on the globe north of the equator. On the ocean from the Earth’s equator, the North Star would be right on the horizon; at the North Pole, it would shine straight overhead.

To find the North Star, look due north (opposite where the Sun is at noon time), and look about half way up in the sky (assuming you live at mid-northern latitudes). On an early February evening, you will see the familiar, brighter, Big Dipper in the northeast. The two stars in the front of the Dipper’s "bowl" appear to point at the North Star, to the left.

This star hasn't always had this distinction.

Polaris just happens to lay very close to the North Celestial Pole, making it seem to be a pivot for the rest of the sky to circle around.Because of a extremely slow wobble of the Earth's axis of rotation, the axis inscribes an imaginary circle on the sky, roughly pointing at different stars along the way to make them the "North Star" (or "South Star" in the Southern Hemisphere). It takes 25,800 years to make this circle, so we have called Polaris the North Star for a very long time.

If you go back 3,000 years, the North Celestial Pole lay very near the star Thuban in the constellation Draco the Dragon. Thuban was the north star when the Egyptians were building the pyramids, and in fact built the pyramids to align with Thuban.